The present invention relates to an armature for a magnetic system, in particular of a switchgear, with a one-piece design and lateral pole faces.
An armature of this type is described in German Patent No. 44 36 832. The armature is designed in the form of a one-piece, magnetically active steel part with an armature plate and a fastening device extending from the latter. It has a bushing for holding a bolt, the bushing being formed by a recess reaching from the bottom of the steel plate into a raised area extending from the latter. The armature is made of a steel block from which the outer contours of the steel plate with the fastening device are milled, as well as, in a further step, a longitudinal opening for creating the bushing. The armature is provided for a magnetic system, in particular a contactor.
The trend toward ever smaller, low-cost solenoid-operated mechanisms, makes it necessary to optimize the geometric dimensions of magnetic systems and reduce the number of parts. To accomplish this, it is advantageous to select the shape of the iron parts so that space can be saved for other elements. The magnetic system armatures designed presently are usually made of steel plates having a uniform thickness. To attach this steel plate to the contact carrier of a contactor, aluminum adapter parts are screwed onto the steel plate in order to reduce mass. If the armature width is to be greatly varied using this technique, the magnetic flux density would enter a state of saturation in partial areas. This produces an elevated magnetic resistance with the known disadvantages in the tensile force variation of the contactor drive.
If this iron saturation is circumvented in partial areas by appropriately adjusting the thickness of the material over the entire part, the result is a larger moving mass, which, in turn, has a negative effect on the drive layout.
To reduce the armature width in only certain areas without increasing flux density it may be possible we could try to improve the arrangement by attaching additional iron parts. However, the armature thickness must be partially increased in this case in order to compensate for the width reduction in the area affected. Retrofitting additional elements, however, creates problems with air gap transitions and the method of connection. Other options, such as milling the part from solid material or producing it by casting, are relatively costly.
An object of the present invention is to provide an armature that can be produced as economically and simply as possible.
According to the present invention, this object is achieved by producing the armature in the form of a sintered part having an H-shaped profile, with the plate-shaped lateral pole faces being interconnected by a central segment which projects over the thickness of both pole faces. A design of this type provides considerable advantages. It allows the armature to have a simple and economical design, providing high-quality surfaces without any later finishing work and simultaneously producing the bushing for holding a bolt. Because the armature may have any desired shape as a sintered part, the flux and mass can be easily optimized.
Due to its H-shaped design and the ability to guide the flux across the thicker central segment, the armature has a space which can be used for other purposes, such as return springs or guides, in the switchgear where the armature will be installed.
The armature is advantageously adjusted to the magnetic flux by having the pole faces tapering toward their edges.